The 6422 optical time-domain reflectometer has the testing capabilities of single mode 1310nm, 1550nm, 1490nm, 1625nm, 1650nm, multimode 850nm, 1300nm, and customized special wavelengths. It can provide multiple modules such as single wavelength, multi wavelength, and online testing, with a maximum dynamic range of 46dB, and can be used for long-distance and multi branch communication network testing of trunk lines; The minimum event blind spot is 0.5m, and the connection situation at the near end can be clearly distinguished; The minimum sampling resolution is 2.5cm, which can accurately locate event points. In addition, it provides a variety of convenient functional options such as stable light source, Optical power meter, visible red light source, optical fiber end face tester, etc.